1. Field of the Invention
The present invention relates to airbag inflation apparatuses for use in motor vehicles and, more specifically, to airbag covers for use in storing airbags.
2. Technical Background
Inflatable airbags have become well accepted in their use in motor vehicles and have been attributed with preventing numerous deaths in accidents. Some statistics estimate that frontal airbags reduce the fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Statistics further suggest that with a combination of seat belt and airbag, serious chest injuries in frontal collisions can be reduced by 65% and serious head injuries by up to 75%. Airbag use presents clear benefits and vehicle owners are frequently willing to pay the added expense for airbags.
A modern airbag apparatus may include an electronic control unit (ECU) and one airbag module or two. The ECU is usually installed in the middle of an automobile, between the passenger and engine compartment. If the vehicle has a driver bag only, the ECU may be mounted in the steering wheel. The ECU includes a sensor which continuously monitors the acceleration and deceleration of the vehicle and sends this information to a processor which processes an algorithm to determine if the vehicle is in an accident situation.
When the processor determines that there is an accident situation, the ECU transmits an electrical current to an initiator in the airbag module. The initiator triggers operation of the inflator or gas generator which, in some embodiments, uses a combination of compressed gas and solid fuel. The inflator inflates a textile airbag to impact a passenger and prevent injury to the passenger. In some airbag apparatuses, the airbag may be fully inflated within 50 thousands of a second and deflated within two tenths of a second.
An airbag cover covers a compartment containing the airbag module and may reside on a steering wheel, dashboard, vehicle door, or vehicle wall. The airbag cover is typically made of a rigid plastic and may be forced opened by the pressure from the deploying airbag. In deploying the airbag, it is preferable to retain the airbag cover to prevent the airbag cover from flying loose in the passenger compartment. If the airbag cover freely moves into the passenger compartment, it may injure a passenger.
Industry is concerned with designing airbag covers in a cost effective manner. Airbag covers which are formed of injection molded parts are economically manufactured and are therefore popular. In one design, the airbag cover is configured with a hinge leg. During deployment the hinge leg retains its engagement to an anchor device to prevent the airbag cover from flying loose into the passenger compartment. A concern, however, is that the hinge leg is made of a rigid plastic material which may tear or otherwise separate during deployment of the airbag.
It would be therefore be an advancement in the art to provide a hinge leg for an airbag cover which better retains the airbag cover during deployment. It would be another advancement in the art to provide a hinge leg with superior resistance to deployment energy. It would be a further advancement in the art to provide an airbag cover with superior resistance while still being composed of an economical material such as plastic. Such a device is disclosed and claimed herein.
The present invention provides an airbag cover with controlled movement during deployment of an airbag. The airbag cover includes a panel member which is configured to cover a compartment housing the airbag apparatus. The panel member may conform to the surrounding surface structure of a dashboard, steering wheel, or other vehicle surface housing the compartment. The airbag cover further includes a breakaway hinge leg connected to the panel member and extending from the panel member in substantially a perpendicular direction. The breakaway hinge leg engages an anchor device to secure the airbag cover during normal operations. The breakaway hinge leg is further configured with a tear seam which separates the breakaway hinge leg into first and second parts upon inflation of the airbag. In this manner, the breakaway hinge leg severs its connection to an anchor upon deployment of an airbag.
The airbag cover further includes a retaining hinge leg connected to the panel member and extending from the panel member in substantially a perpendicular direction. The retaining hinge leg may be disposed parallel to the breakaway hinge leg. The retaining hinge leg is configured to engage an anchor device to retain the panel member during normal and accident conditions.
The retaining hinge leg is further configured with a plurality of energy-management apertures. During deployment of an airbag, the energy-management apertures receive energy from the deploying airbag and control it such that the cover hinge leg remains completely or partially attached to prevent the separation of the retaining hinge leg from the panel member which may result in free movement of the panel member.
An energy-management aperture adjacent or in the path of a tear provides relief by increasing the stretch capability of the retaining hinge leg. An energy-management aperture in an elliptical pattern provides relief by causing the energy to cancel itself out rather than tear through the hinge leg. Thus, the energy-management aperture obstructs the tear and resists further tearing. The energy-management apertures may be disposed singularly or in a group. In some embodiments, apertures are strategically disposed in linear series to provide added resistance to tearing or to increase the likelihood of intercepting a tear.
Conversely, the energy-management apertures can induce tearing in a location so as to prevent tearing elsewhere on the hinge leg. Induced tearing in a hinge leg may prevent complete separation of the cover from the retaining hinge leg during deployment of an airbag.
As airbag covers are made from rigid plastics, the retaining hinge leg is susceptible to tearing during deployment. Energy-management apertures on the retaining hinge leg are an economical and efficient means to reduce airbag cover/door weight while maximizing the stress/strain characteristics of the associated hinge legs.
Airbag covers generally are susceptible to sink marks where a hinge leg thickness exceeds the thickness of a cover. This is termed as the cover to hinge leg sink ratios. Energy-management apertures allow for a thinner hinge leg thickness resulting in improved cover aesthetics.
These and other features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.